Origin of the dual rate- and phase codes of space in the hippocampus and medial entorhinal cortex

空间在海马体形成中的神经元表现为位置选择性神经元的放电速率和与局部场电位振荡相关的尖峰时间。存在大量的理论模型，为海马体形成的几个部分的两种代码提供了可能的机制解释。在这个项目中，我们分析了来自合作者实验室的数据，这些数据来自海马或内嗅损伤的动物。由于这两个脑区在一个回路中连接，受损的动物提供了一个理想的模型系统来研究单独在单个脑区发生的计算。初步结果表明，内侧内嗅皮层对海马的时间关系尤为重要，而与目前的看法相反，它几乎不影响速率码。分析海马损伤动物的内嗅皮层神经元的记录，使我们能够完善网格场形成的当前理论模型。特别是减少特定地点的放电需要一种新的建模方法。在这个项目中，我们将开发一种新的基于尖峰的内嗅网格细胞模型，该模型将通过海马损伤动物的数据进行交叉检查。

Space is neuronally represented in the hippocampal formation both in the firing rate of place-selective neurons and the spike timing with respect to the local field potential oscillation. A multitude of theoretical models exist, which provide possible mechanistic explanations of both codes in several parts of the hippocampal formation. In this project we analyse data from the laboratory of our collaborator, from animals with either hippocampal or medial entorhinal lesions. Since these two brain areas are connected in a loop, the lesioned animals provide an ideal model system to study the computations occurring in the individual brain areas alone. Preliminary results indicate that the medial entorhinal cortex is particularly important for the timing relations in the hippocampus, whereas, in contrast to current believe, it hardly affects the rate code. Analyzing recordings of medial entorhinal cortex neurons in hippocampus-lesioned animals allow us to refine current theoretical models of grid field formation. Particularly the reduction of place-specific firing asks for a new modeling approach. In this project we will develop a new spike-based model of entorhinal grid cells that will be cross-checked by data from hippocampus-lesioned animals.